void MessageSpefications::parseBuffer(unsigned char *buf){
     spf_vector.assign(length, Specification() );
     channels = *buf;
     buf++;
     for(int chnl=0;chnl<channels;chnl++)
      { Specification spf;
        spf.setChannel(chnl);
        spf.setCurrent(*((float *)(buf)));
        spf.setVoltage(*((float *)(buf+4)));
        spf_vector.push_back(spf);
        buf+=8;
      }
}